1. Field of the Invention
The present invention generally relates to barrel nuts used to mount a forward hand guard assembly around the barrel of a rifle, particularly to a multi-caliber quick-change coupler assembly which is used to secure a rifle barrel to the upper receiver of a rifle while also allowing prompt access to the barrel and quick barrel change, and which further can be used to mount almost every hand guard assembly currently marketed to the upper receiver of the AR family of rifles.
The present invention multi-caliber quick-change coupler assembly comprises a barrel nut and a two-piece separable extension with a secure but promptly releasable threaded connection between them. The barrel nut has a generally cylindrical and open-ended configuration, approximately half of which has interior threads that extend from its receiver end centrally into the barrel nut. The portion of the interior threads adjacent to its receiver end is used for secure connection of the barrel nut to the forward end of the upper receiver of a rifle, while the interior threads more centrally positioned within the barrel nut are used for repeat engagement and release of the two-piece separable extension to lock the flange of a rifle barrel against the rifle's upper receiver as portions of the barrel adjacent to the flange extend through the barrel nut, the two-piece extension, and the rifle's upper receiver. Once connection of the two-piece extension to the barrel nut is released through the use of a hand guard supported fastener-tool, spanner wrench, or by other means, the two pieces of the extension are immediately separable from one another and after such separation can be easily lifted away from the rifle barrel while the barrel remains extending through the present invention barrel nut, which still has a threaded connection to the rifle's upper receiver. Also, since the barrel's flange is no longer locked against the upper receiver by the two-piece extension, the rifle barrel is easily pulled through the present invention barrel nut and away from both the upper receiver and the barrel nut.
During rifle use, the threaded connection between the present invention two-piece extension and barrel nut is further secured by set screws extending through fastener holes in the barrel nut and engaging the exterior surface of the two-piece extension, which while providing anti-rotational engagement between the two-piece extension and the barrel nut during rifle use also allows prompt separation of the two-piece extension from the barrel nut for quick barrel change, particularly when a fastener-tool with a tool end configured for set screw attachment and release is stored/carried by a hand guard assembly mounted upon the barrel nut where it is immediately available to the hunter or outdoorsman carrying the rifle. Also, to facilitate quick barrel change, the present invention barrel nut purposefully has no interior threads at or near its barrel end, allowing the exterior threads on the outside surface of the two-piece extension to quickly pass through the non-threaded interior surface on the barrel end of the barrel nut before reaching and becoming engaged with the centrally-located portion of the barrel nut's interior threads. Furthermore, for mounting a hand guard assembly around a rifle barrel when the present invention coupler assembly is used to secure the rifle barrel into its needed position of use, the present invention barrel nut also comprises a plurality of radially-extending and gear-like exterior teeth centrally around its exterior circumference. An external groove is also provided on the receiver end of the present invention barrel nut to assist in the mounting of older hand guard assemblies, so that almost every hand guard assembly currently marketed can be mounted to the upper receiver of the AR family of rifles. No similar structure is currently known in the prior art, nor one that provides the same benefits and advantages as the present invention.
2. Description of the Related Art
Use of forward hand guards for rifles is now common and provides multiple advantages. They insulate the shooter's hand from the heat of a rifle barrel. They also can include provisions (such as groove sets on one or more of its sides commonly referred to as a rail) for mounting accessories to the rifle such as, for example, a flashlight aligned with the barrel to illuminate the area in front of the weapon in low light. On early rifles, accessory mounting devices were almost exclusively employed for mounting telescopic sights and were thus provided mainly on the top portion of the rifle's receiver. However, commonly today for militarized assault rifles such as the M16, accessory mounting provisions are found on the hand guard (commonly known as Picatinny rails since they were developed at the Picatinny Arsenal), with one or more Picatinny rails typically found on each hand guard. Picatinny rails are standardized in structure, with dimensional specifications found in MIL-STD-1913 or ST ANAG 2324. Hand guards may be either permanently mounted to the weapon, or they may employ a “quick-attach/quick-detach” design that allows prompt separation into two parts once fasteners or other connection is released. Examples of firearms usable with the present invention coupler assembly include the AR family of automatic rifles, including but not limited to the AR 15, AR 18, AR 10, and AR 7, as well as rifles having the following caliber designations 5 mm, 17 caliber, 5.7 mm 22 short, 22 long rifle, 22 Magnum, .224 caliber, .223 caliber, 5.56 mm, 5.7 mm, 204 Ruger, 6.8 mm, 300 Whisper 300 Blackout, 7.62×39, .308 caliber, 7.62×51, 7.62×54, 338 federal, 243 caliber, 260 Remington, 6.5 mm, and 6.5 Creedmore. By providing structure not otherwise known in the prior art, the present invention coupler assembly is able to mount almost every hand guard currently marketed to the upper receivers of the AR family of rifles, and to other rifles as well, while also providing the additional advantage of quick barrel change.